The Command Pattern

Why?

Models (@colyseus/schema) should contain only data, without game logic.
Rooms should have a little code as possible, and forward actions to other structures

The command pattern has several advantages, such as:

It decouples the classes that invoke the operation from the object that knows how to execute the operation.
It allows you to create a sequence of commands by providing a queue system.
Implementing extensions to add a new command is easy and can be done without changing the existing code.
Have strict control over how and when commands are invoked.
The code is easier to use, understand and test since the commands simplify the code.

Usage¶

Installation

npm install --save @colyseus/command

Initialize the dispatcher in your room implementation:

import { Room } from "colyseus";
import { Dispatcher } from "@colyseus/command";

class MyRoom extends Room<YourState> {
  dispatcher = new Dispatcher(this);

  onCreate() {
    this.setState(new YourState());
  }

  onJoin(client, options) {
    this.dispatcher.dispatch(new OnJoinCommand(), { sessionId: client.sessionId });
  }

  onDispose() {
    this.dispatcher.stop();
  }
}

How a command implementation looks like:

import { Command } from "@colyseus/command";

export class OnJoinCommand extends Command<YourState, { sessionId: string }> {
  execute({ sessionId }) {
    this.state.players[sessionId] = new Player();
  }
}

See more¶

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